# Re: ISIS and its fit statistics

From: John Houck <houck_at_email.domain.hidden>
Date: Sat, 7 Feb 2004 13:17:46 -0500
On Fri, Jan 30, 2004 at 10:12 -0800, FIll Humphrey wrote:
> To whom it may concern...

Apologies for the slow reply -- I was traveling last week
and away from my email.

[...]
> 1. In the computation of the cash statistic (cash.c in the code?), I've
> run into a serious issue if the model in any bin hits zero. To whit, in
[...]

I think you're right -- I'll fix this in the next release.

>
> 2. For both the Cash and \chi^2 fit statistics, to my very inexperienced
> reading of the code, neither seem to take into account the errors on the
> background you read in. Is this correct? I've noticed tangible differences
[...]

This is correct; it works this way for historical reasons, but
it is something that should be corrected.  I will try to work
this fix into the next release as well.

Thanks,
-John

--
John C. Houck                       MIT Center for Space Research
NE80-6005: 617-253-3849                   77 Massachusetts Avenue
42:21:55.105N, 71:05:28.122W             Cambridge, MA 02139-4307
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Received on Sat Feb 07 2004 - 13:18:17 EST

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